Improve @material-ui includes.

[WiXSL]

Refs #4253

[fzaninotto]

We won't merge the changes to the @material-ui/core imports. Our developer experience is also important, and the "one line per component import" is just too cumbersome. Besides, the performance issue only concerns icons. So please just change the 2 instances of @material-ui/icons import.

[WiXSL]

Ok.
At least could I include one liners like:

- import { useMediaQuery } from '@material-ui/core';
+ import useMediaQuery from '@material-ui/core/useMediaQuery';

- import { makeStyles } from '@material-ui/core';
+ import { makeStyles } from '@material-ui/core/styles';

[fzaninotto]

No thanks, I'll merge it as is. I don't want to introduce two syntax for importing from @material-ui/core.

[fzaninotto]

Thanks!